With the popularity of intelligent lamps, a more efficient and humanized product is expected by more and more customers hoping that the lamp can be turned off automatically when external light exceeds a certain lux level and turned on automatically when external light is lower than the preset lux level; or it can adjust the lighting intensity automatically according to the environmental illumination to realize the interaction between artificial light and natural light and thus achieve the effect of intelligent lighting control. Therefore, the manufacturers of lamps are expecting that a sensor for light sensation detection may be built in a lamp so as to add the function of intelligent control, maintain the appearance of the lamp, and also reduce the cost of wiring and installation difficulty for end-users.
However, the built-in photoelectric sensor may receive both the external natural spectrum and the artificial spectrum emitted by the lamp. Moreover, the visible light intensity of the artificial spectrum emitted or reflected through the translucent cover of the lamp is far greater than that of the surrounding natural spectrum. Meanwhile, the lux level of the invisible light in the artificial spectrum will change with the color temperature; the lower the color temperature of the lighting source is, the higher the lux level of the invisible light will be. Such built-in sensor cannot detect the intensity of surrounding natural light accurately through ordinary light detecting method, thus the function of brightness control and turn-off control of the lamp cannot be realized according to actual intensity of natural light. Most built-in sensors on the market at present cannot detect the lux level of the lamp itself. In case the threshold value of environmental natural light for turning on the lamp is lower than the preset lux level, such as at dawn, the lamp will be activated and keep on lighting if people pass by frequently. As the actual lux level of the natural light cannot be detected while the lamp is lighted, the lamp will not be turned off even if the external natural light is bright, thus the energy is wasted. For this problem and the actual demand, the lamp and the sensor are normally arranged separately. For example, the light sensor is kept far away from the lamp by leading out through a leading wire so that it can collect the natural light only. As for such scheme, the size and installation structure of the lamp will be redesigned and re-customized and the overall appearance of the lamp will be affected, resulting in high costs, therefore, it is to promote the lamp on a large scale.